Experts are already arguing over how to rebuild Notre Dame

Less than 48 hours after firefighters extinguished the blaze at Notre Dame, Emmanuel Macron is already shifting the country's attention to the next mammoth task at hand: rebuilding.

France’s president has called for the beloved 850-year-old cathedral to be fully rebuilt within five years, and announced an architecture competition for a new design for the iconic spire, which collapsed in Monday’s devastating nine-hour blaze.

But as the reconstruction gets under way, big questions about how to go about it are already spurring debates among cathedral experts. How do you rebuild a structure that has stood for centuries as an emblem of French identity, surviving wars, Nazis, and acid rain? Will the French strive for absolute authenticity, or push forward with contemporary materials and designs?

“There will be people that will constantly argue that it should be brought back to its original state,” said James Patterson, the director of facilities and capital projects at the Cathedral of St. John the Divine in New York City. “It’s the inside of the cathedral that counts, not necessarily the structure.”

The goal, Patterson said, should be to protect the church from future fires while maintaining authenticity to the degree possible. The original, oak forests that supplied the timber for the original construction no longer exist, so they’ll need to use somewhat different materials anyway, Patterson said.

Not everyone who works with cathedrals agrees. John David, the master mason at York Minster, a cathedral in York, England, whose roof burned down in 1984 and has since been rebuilt, hopes to see a wooden roof back on Notre Dame.

“Hopefully, from our point of view, they will restore the actual rest of the building with traditional materials — the stone, by hand, and the woodwork,” David said. “They will restrict the roof space to prevent fire from spreading, but I hope they’ll use traditional oak and timber materials.”

It’s not just the materials used that may prove controversial but also the building methods, too. “They could invoke all of today’s technologies, including robot stone-cutting, to rebuild it,” said Mark Burry, the director of the Smart Cities Research Institute of Swinburne University. Burry was a lead architect on the Sagrada Familia in Barcelona for 38 years, until 2016. That cathedral, which has been a work in progress for over 130 years, now employs many of these modern techniques in its ongoing construction.

But according to David, using robot-cut stone could produce stonework that doesn’t look like the original. “When you get that done on an existing building which has been crafted by hand, it stands out like a sore thumb,” he said. "It needs to be done by hand."

Contemporary technology could also open up new options not just about the methods of rebuilding, but what to strive for. There’s likely so much data on Notre Dame that the most minute details of the structure could be restored to the way they were just before the fire.

“If it’s been 3-D scanned, that means you could actually even replicate every single little crack, every single little fissure.” Burry said. “It becomes a real dilemma. Do you artificially distress it to mimic it as it was the day before it burned in the fire, or do you pretend that you have the opportunity of restoring it to what it would have been like the day after it was finished in the 13th century?”

The methods that officials choose will determine how long it ultimately takes to rebuild. Burry, who argues that contemporary technologies could be used, thinks Macron’s five-year deadline for the rebuilding of the cathedral is a little tight, but feasible. For David, however, that deadline seems completely unreasonable.

“If you want to do it in five years, it won’t be done in the traditional way, and I think they would have to cut corners,” David said.

"This shouldn't be treated as a political aid. It's beyond politics. It's France. For anyone trying to get political brownie points out of it, it’s completely unfair.”

Even if the new Notre Dame isn’t rebuilt exactly to its old specs, the version of the cathedral as it was on the day before the fire could still live on digitally. Barry Threw, the director of a project called New Palmyra, which is working to create a digital version of ruins in Palmyra, Syria, which have been partially destroyed by ISIS, is already starting work on a new effort, focused on Notre Dame.

“We’ll be offering people the opportunity to contribute by uploading their own photos of the Notre Dame site,” Threw said. “And through a process photogrammetry, which uses machine-learning and computer reconstruction, we can create a 3D model out of thousands of crowd-sourced pictures.”

But for now, there are more immediate concerns. Without a roof, the cathedral’s interior will be exposed to the elements, and could be damaged further. The first thing that the French will have to do is put up a temporary roof and assess the damage. Only then will they be equipped to start thinking about how long the project might take, how much it will cost, or what materials should be used.

“It will get done quickly, in what I consider to be cathedral time,” Patterson said. “Nothing in a cathedral is done overnight. Everything takes time.”

Cover: People look at blaze-hit Notre Dame Cathedral in Paris on April 16, 2019. (Kyodo via AP Images)